Why are formula triangles bad?

Formula triangles are a tool to help students use equations without needing to rearrange them. To use one, cover up the term you’re trying to find to reveal the expression required to calculate it. In the example here it’s the volume: cover up V to see the required equation is moles divided by concentration. Or if you want the number of moles, cover up the n and then, as c and V are side by side, multiply them together.

I dislike formula triangles for a number of reasons. My experience in the admissions interview is not uncommon. While they may be a useful approach for A-level exams (these candidates all had A or A* at chemistry A-level) it doesn’t seem to help much in the long term. In my experience the most successful approach to rearranging equations is the balance method. 

Jenny Koenig demonstrates and explains how teachers can help students learn to rearrange equations, providing a link to equation question sets for use with this topic.